bbbb bbdd bd-r bdii bibb bibi bidi bidr bidu birb bird biri birr birt biru bitd bitt bitu brdt brid brit brrr brud brut btdt btrt bttb bubb bubi bubu budb budd budi budu buid buir buit buiu bur- burb burd buri burr burt buru but- buti butt dbit dbtt dddd ddub dibb didi didu diii dird dirr dirt diti ditt drib drit drub drui drut druu dub- dubb dubu dudd dudu duid duir duit duri durt duru duur duut ibid ibrd ibri ibtb idid idir idub iiii iiit iitr iitt iri- irid irri irti itri itur iuiu rbbb rbbr rib- ribu ridd ridi riri riti ritt ritu rrrr rtdt rubb rubi rubu rudd rudi ruid ruit rurd ruri ruru ruti rutt rutu ruud tbit tbrb tddb tdri tibi tibu tidd tiit tiiu tirb tird tiri tirr tiru titi titt titu tri- trib trit trtr trub trud trut truu ttbb tttt tubb tubr tubu tudi tudu tuit tuiu turb turd turi turr turt turu tuti tutt tutu ubbi ubid ubii ubir ubit ubud uddi udid udir uirr urbi urdu urib uriu urri urur urut utid utri utti uttu uuri uuuu